Assemblies, wherein two or more housings are secured together by bolts and subjected through a dynamic input force, such as the vibration from an engine, require that the bolts be designed, such that the natural frequency thereof is outside the operating range of the dynamic force source.
As a general rule, the designer will provide attaching structures to the housings which will permit the use of shorter bolts to thereby increase the natural frequency of each bolt. In multiple housing assemblies, it often becomes necessary to bolt one housing to another before bolting the combined housings to a final assembly. This, of course, requires more fasteners than is otherwise necessary, and it also requires providing the space to allow the bolts to be utilized. This creates some problems when the same base housing is used in different assemblies, wherein longer bolts are required to complete the assembly.